- Patients with QTc (corrected QT interval) interval greater than 450 msecs or other factors that increase the risk of QT (Q wave, T wave) prolongation or arrhythmic events (e.g., heart failure, hypokalemia, family history of long QT interval syndrome) including heart failure that meets New York Heart Association (NYHA) class III and IV definitions are excluded. This does not include QTc prolongation secondary to a paced rhythm. If a patient has a paced rhythm, QTc levels less than or equal to 500 (Grade 1) are allowed and patients with QTc > 500 are excluded.